The instant invention relates to folding of a collation of paper sheets, and more particularly to the folding of a collation having more sheets than the folding apparatus can fold together simultaneously.
There is a need in the area of folding of paper sheets by means of buckle chute folders to be able to fold together a relatively large number, such as 20, 30 or more, of paper sheets or documents. This requirement comes about by virtue of businesses, such as utilities or banks or retail stores, having large statements or bills which in many cases may exceed 20 or more sheets of paper, most or all of which may need to be folded in order to be inserted into an envelope for mailing to a customer. Typically, the feeding of the sheets of paper, the folding of the sheets of paper, and the insertion of the folded sheets of paper into the envelope are effected by an inserting system comprising document feeders, accumulators, buckle chute folders and envelope feeders and inserters.
A critical limitation with the aforesaid state of the art inserting system is the inability to fold a large number of sheets together simultaneously. Some of the most critical limitations are the noise of the sheets of paper entering and leaving the folding rollers and the tremendous force required to maintain pressure of the folding rollers relative to each other as they separate to accept a large number of sheets together.
One solution to the foregoing problem is described in U.S. Pat. No. 4,898,570 issued Feb. 6, 1990 to the assignee of the instant invention, and is known as shingle folding. In this folding method, the sheets of a packet are folded sequentially, offset from each other by about 20% of the length of a sheet of paper, and the sheets are then nested together following the folding process. The drawback to this method is a lack of speed. Because of the shingling of the collation, the speed of the collation going through the folder is reduced by almost 50%.
It is known to divide a large collation into sub-sets, fold the sub-sets separately, and then combine the sub-sets for insertion into an envelope. However, the use of sub-sets does not take into account an address bearing However, the use of sub-sets does not take into account an address bearing sheet, which must appear, for many applications, on the top of the collation, face up. The normal process of sub-setting and folding would result in the address bearing sheet winding up in a position other then on the top of collation, face up.
Accordingly, the instant invention provides a method of sub-setting a large collation of sheets, folding the sub-sets, and re-combining the sub-sets so that the address bearing sheet winds up as the top sheet, face up. The final collation now has an address which can appear through the window of an envelope, or simply be located properly for reading by the recipient of the envelope.